Instance Methodswift-png 4.4.5PNG

premultiplied(as:)

The color obtained by premultiplying the red, green, and blue components of this color with its alpha channel, performing the premultiplication in the given integer type.

PNG.RGBA.swift:146

func premultiplied<U>(as _: U.Type) -> PNG.RGBA<T> where U : FixedWidthInteger, U : UnsignedInteger

Mangled symbol

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FNV24: [2A2VD]

Constraints

where T:UnsignedInteger, T:FixedWidthInteger

Parameters

_: The integer type to perform the premultiplications in. U.bitWidth must be less than T.bitWidth.

Returns

The premultiplied color.

Premultiplication in a different integer type is sometimes necessary to reproduce the output of other image processing frameworks.

The premultiplied color is obtained by invoking premultiply(_:alpha:) on r, g, and b, after scaling them to the range of U. The returned components are then scaled back to the range of T. The rescaling operation also affects the a component.

Other members in extension

Typealiases

typealias Aggregate
Palette aggregates are (red, green, blue, alpha) quadruplets.

Type members

init(PNG.VA<T>)
Creates an RGBA color from a grayscale-alpha color.
init(T)
Creates an opaque, monochromatic RGBA color.
init(T, T)
Creates a monochromatic RGBA color.
init(T, T, T)
Creates an opaque RGBA color.
init(T, T, T, T)
Creates an RGBA color.
static func pack([`Self`], as: PNG.Format, indexer: ([(r: UInt8, g: UInt8, b: UInt8, a: UInt8)]) -> (Aggregate) -> Int) -> [UInt8]
Packs an array of RGBA pixels to an image data storage buffer.
static func unpack([UInt8], of: PNG.Format, deindexer: ([(r: UInt8, g: UInt8, b: UInt8, a: UInt8)]) -> (Int) -> Aggregate) -> [`Self`]
Unpacks an image data storage buffer to an array of RGBA pixels.

Instance members

var premultiplied: `Self`
The color obtained by premultiplying the red, green, and blue components of this color with its alpha channel.
var straightened: `Self`
The color obtained by straightening the red, green, and blue components of this color according to its alpha channel.
var va: PNG.VA<T>
The grayscale-alpha color obtained by discarding the green and blue components of this color.
func straightened<U>(as: U.Type) -> PNG.RGBA<T>
The color obtained by straightening the red, green, and blue components of this color according to its alpha channel, performing the straightening in the given integer type.